Cardioplegia balloon cannula

ABSTRACT

A cardioplegia occluder and methods of using the device during cardiac surgery are disclosed. The system typically includes a substantially rigid cannula with an occluder mounted on the distal region of the cannula that expands upon activation to occlude the aorta downstream of an infusion port which delivers cardioplegia solution to arrest the heart. Systems including cutting blades, blade guards, flanges, radiopaque markers and occluder aligners are also disclosed. In use, the distal end of the cannula is inserted through an incision into the aorta, the occluder is expanded and cardioplegia solution is infused upstream of the aorta to arrest the heart. The infusion port can alternately be used to aspirate cardioplegia or embolic debris or other unwanted material from the aorta.

This is a continuation-in-part of U.S. application Ser. No. 09/387,634,filed Aug. 31, 1999, and presently allowed, which is a continuation ofU.S. application Ser. No. 08/993,202, now U.S. Pat. No.6,048,331, filedDec. 18, 1997, which is a continuation-in-part of still pending U.S.application Ser. No. 08/854,806, filed May 12, 1997, which is acontinuation-in-part of U.S. application Ser. No. 08/645,762, filed May14, 1996, now abandoned. The contents of each of these priorapplications are expressly incorporated herein by reference in theirentirety.

FIELD OF THE INVENTION

This invention relates to methods and apparatus for administeringcardioplegia to the aorta during cardiac surgery. The devices include acardioplegia occluder that can include various features such as acutting blade, a blade guard, a flange, radiopaque markers and anoccluder aligner to properly position the distal end of the devicewithin the aorta. Once the cardioplegia occluder is in its properposition, the occluder is expanded to occlude the aorta downstream ofthe infusion port and cardioplegia solution is then introduced throughthe infusion port to arrest the heart. The infusion port can alternatelybe used to aspirate cardioplegia or embolic debris or other unwantedmaterial from the aorta.

BACKGROUND

Currently, the most common method of temporarily occluding the ascendingaorta and arresting the heart during open heart surgery utilizes amechanical cross clamp and a cardioplegia cannula. Once the chest cavityhas been opened, access to the heart and to the adjacent vessels isprovided. The ascending aorta is partially dissected from thesurrounding tissue and exposed. Arterial and venous cannulas areinserted and sutured into place. The cannulas are connected to thecardiopulmonary bypass machine, and bypass blood oxygenation isestablished.

At this point, the heart must be arrested and isolated from the rest ofthe circulatory system. A mechanical cross clamp is positioned betweenthe cardioplegia cannula and the aortic cannula and is actuated. Theaorta is completely collapsed at the clamp site, thus stopping flow ofblood between the coronary arteries and the innominate artery, and theoxygenated bypass blood is shunted around the heart. Once the vesselocclusion has been completed, cardioplegia solution is introducedthrough the cardioplegia cannula to arrest the heart. The surgeon maynow proceed with the desired operation.

Other less common means of occluding the aorta include percutaneousballoon catheter occlusion, direct aortic balloon catheter (Foley)occlusion, aortic balloon catheter occlusion, and an inflating diaphragmoccluder (Hill—occlusion trocar). The percutaneous balloon catheter isinserted typically from the femoral artery feed through the descendingaorta, across the aortic arch into position in the ascending aorta. Oncein the ascending aorta, the balloon occluder is inflated and flowstopped.

As a simple replacement for the mechanical cross clamp, a Foley cathetermay be placed through an additional incision site near the standardcross clamp site. Once inserted, the Foley catheter balloon is inflatedand flow is stopped. Similarly, an aortic balloon catheter is placeddirectly into the aorta. This catheter replaces the standard aorticcannula by delivering the CPB blood back to the arterial circulatorysystem. The occluder balloon is located on the catheter proximal to CPBblood exit port on the cannula. The occlusion trocar is desired to offersimilar features as the aortic balloon occluder cannula and would beused in place of the standard aortic cannula. However, it relies on aninflatable diaphragm to occlude the vessel.

The use of a balloon to occlude an artery has been disclosed by Gabbay,U.S. Pat. No. 5,330,451 (this and all other references cited herein areexpressly incorporated by reference as if fully set forth in theirentirety herein). The Gabbay device included a perfusion cannula havinga proximal balloon occluder and a distal intra-aortic balloon to divertblood to the carotid arteries. The Gabbay perfusion cannula is disclosedfor use during open heart surgery in order to prevent complicationsassociated therewith.

Moreover, Peters, U.S. Pat. No. 5,433,700, discusses a method forinducing cardioplegic arrest using an arterial balloon catheter toocclude the ascending aorta. The Peters method includes the steps ofmaintaining systemic circulation using peripheral cardiopulmonarybypass, venting the left side of the heart, and introducing acardioplegic agent into the coronary circulation. This procedure is saidto prepare the heart for a variety of surgical procedures. Disclosuresof similar endovascular occlusion catheters can be found in Machold etal., U.S. Pat. No. 5,458,574, Stevens, International Application No.PCT/US93/12323, Stevens et al., International Application No.PCT/US94/12986, Nasu, U.S. Pat. No. 5,425,708 and Grinfeld et al., U.S.Pat. No. 5,312,344.

Each of the existing methods of blocking aortic blood flow and arrestingthe heart carries with it some undesired aspects. The mechanical crossclamp offers simplicity and reliably consistent operation. However, thephysical clamping action on the vessel has been linked to many adversebody responses. Barbut et al. (“Cerebral Emboli Detected During BypassSurgery Are Associated With Clamp Removal,” Stroke, 25(12):2398-2402(1994), incorporated herein by reference in its entirety) noted themajority of embolic events (release) is associated with the actuationand release of the cross clamp during coronary bypass graph surgery. Theclamping action may be responsible for breaking up and freeingatherosclerotic buildup on the vessel walls. In addition, the potentialfor vascular damage, like aortic dissections, may also incur during theclamp application.

The percutaneous balloon catheter occluder has a distinct drawback inthat it must be placed with visionary assistance. Fluoroscopy istypically used to position the device in the aorta. This added equipmentis not always readily available in the surgical suite. In addition, thecatheter placement up to the aorta may also create additional vasculartrauma and emboli generation.

The use of a Foley catheter to occlude the aorta requires an additionalincision site to place the device. The extra cut is an additional insultsite and requires sutures to close. Generation of emboli and thepotential of aortic dissection directly associated with just theincision may potentially outweigh the benefits of using the catheter.

The aortic balloon occluder cannula addresses many of the deficienciesof the previous devices. Placement is easy to visualize, no extra cutsare required, and there is no need for the potentially traumatic crossclamp. However the currently-available aortic balloon occluders sufferfrom problems of migration within the ascending aorta because thecannulas on which the balloons are mounted are typically flexible tubesas disclosed by Grinfeld et al. and Nasu. Attempts to solve themigration problem include balloon designs with a large “footprint” inthe distal region of the cannula. (See Nasu, supra.) This largefootprint balloon is a less than adequate solution because it encroachesinto the already limited area of the ascending aorta in which surgicalaccess is available. Further, use of each of these aortic occludingballoons requires a cardioplegia cannula to be inserted through anadditional incision site to arrest the heart.

A need exists for an aortic cannula having both a balloon occluder whichcan isolate the ascending aorta from peripheral vasculature withoutsubstantial migration of the occluder into the ascending aorta, therebyreducing or eliminating the need for aortic cross-clamping, and anassociated cardioplegia infusion port which eliminates the need for aseparate incision for a cardioplegia cannula. Existing devices areinadequate for this purpose.

SUMMARY OF THE INVENTION

The present invention relates to medical devices and their methods ofuse, and particularly cardioplegia occluders. The cardioplegia occluderscomprise a cannula having an occluder to isolate the ascending aortafrom peripheral vasculature during cardiac surgery and an infusion portfor administering cardioplegia to arrest the heart. The infusion portcan alternately be used to aspirate cardioplegia or embolic debris orother unwanted material from the aorta. The devices of the presentinvention may include various features such as a cutting blade, a bladeguard, a flange, radiopaque markers and an occluder aligner to properlyposition the distal end of the device within the aorta.

In one embodiment, the device includes a substantially rigid cannulaadapted to enter the aorta with a proximal end that receivescardioplegia solution into a cardioplegia lumen and delivers it to aninfusion port in the distal region of the cannula. An occluder, mountedon the distal region of the cannula, expands away from the cannula uponactivation to substantially occlude the aorta downstream from theinfusion port. During use, the occluder isolates the ascending aortafrom the peripheral vasculature. The substantially rigid nature of thecannula inhibits migration of the occluder into the ascending aorta,thus overcoming problems associated with other currently availableaortic balloon cannulas. In certain embodiments, the occluder is aninflatable balloon. In other embodiments, the occluder is a foam-filled,self-expanding balloon. Certain balloon embodiments also include a lumenwhich can be used to inflate the balloon or alternately can be used toapply negative pressure to deflate the balloon. Other embodimentsinclude an aspiration lumen which terminates at the infusion port sothat the infusion port can alternately be used to deliver cardioplegiasolution or aspirate embolic debris and other unwanted material from theaorta. Another embodiment further includes an occluder aligner to helpposition the distal end of the cannula within the aorta and to stabilizethe position of the occluder during expansion. In another embodiment,the device includes a cannula associated with a cutting blade which isadapted to cut through the wall of the aorta to allow introduction ofthe cannula. The proximal end of the cannula is adapted to receivecardioplegia solution into a cardioplegia lumen and deliver it to aninfusion port in the distal region of the cannula. An occluder mountedon the distal region of the cannula expands away from the cannula uponactivation to substantially occlude the aorta downstream from theinfusion port. During use, the occluder isolates the ascending aortafrom the peripheral vasculature. Certain embodiments also include ablade guard which moves when pressed against the aorta to allow theblade to cut through the wall of the aorta and then repositions toprevent the blade from cutting. Other embodiments further include anoccluder aligner, a lumen which can be used to inflate the or deflatethe balloon or an aspiration lumen which terminates with the infusionport.

The methods of the present invention include administering cardioplegiato the aorta during cardiac surgery using a cardioplegia occluder asdescribed above. An incision is made in the aorta, and the distal end ofthe cannula is inserted through the incision. The occluder is expandedto occlude the aorta and thereby isolate the ascending aorta fromperipheral circulation without substantial migration of the occluderwithin the ascending aorta. Cardioplegia solution is then infusedthrough the infusion port to arrest the heart. In embodiments thatinclude a cutting blade, the step of making the incision in the aorta isperformed by the cutting blade. In embodiments that include anaspiration lumen, the method further includes the step of aspiratingcardioplegia and embolic debris from the aorta by applying negativepressure to the aspiration lumen.

BRIEF DESCRIPTION OF DRAWINGS

Reference is now made to a brief description of the drawings, which areintended to illustrate a cardioplegia occluder for use herein. Thedrawings and detailed description which follow are intended to be merelyillustrative and are not intended to limit the scope of the invention asset forth in the appended claims.

FIG. 1 depicts an embodiment of a cardioplegia occluder with a cannulahaving three lumens.

FIG. 2 depicts a lateral cross-section of the distal region of theembodiment of FIG. 1.

FIG. 3 depicts another embodiment of a cardioplegia occluder with acutting blade and a retractable blade guard.

FIG. 4 depicts a lateral cross-section of the distal region of theembodiment of FIG. 3.

FIG. 5 depicts an embodiment of a cannula with a side channel having acardioplegia occluder.

FIG. 6 shows the cardioplegia occluder inserted into the aorta via aminimally invasive chest port.

FIG. 7 depicts a lateral cross-section of an embodiment having anL-shaped cannula with infusion ports proximal to the occluder.

FIG. 7A depicts a lateral cross-section of an embodiment having anL-shaped cannula with an infusion port at the distal end of the cannula.

FIG. 8 shows a lateral view of an embodiment with a separatelyinsertable balloon cannula, a separately insertable filter cannula and aseparately insertable cutting blade.

FIG. 9 depicts a lateral cross-section of an embodiment with an angledretractable cutting blade.

FIG. 10 depicts a lateral cross-section of an embodiment with aspring-mounted retractable cutting blade and a curved distal region ofthe cannula which can serve as a blade guard.

FIG. 10A depicts a lateral cross-section of an embodiment where the endof the distal region is sharpened to form a cutting blade and the bladeguard is a retractable obturator received through the cutting blade.

FIG. 11 shows a lateral cross-section of an embodiment with a ballooncannula slideably inserted in a flange sleeve where the distal end ofthe flange sleeve is sharpened to form a cutting blade.

FIG. 12 shows the embodiment of FIG. 11 where the balloon cannula andthe expanded occluder have advanced beyond the distal end of the flangesleeve and into the vessel.

FIG. 13 shows lateral cross-section of an embodiment with an exposedcutting blade and a cannula with a collapsed occluder positioned insidethe flange sleeve.

FIG. 13A shows the embodiment of FIG. 13 where the cannula and theexpanded occluder have advanced beyond the end of the flange sleeve andinto the vessel, and the cutting blade is retracted inside the distalend of the cannula.

FIG. 14 depicts a lateral cross-section of an embodiment partiallyinserted into a vessel where the embodiment includes a detachableintermediate flange containing a cannula with a collapsed occluder andan exposed cutting blade.

FIG. 14A depicts the embodiment of FIG. 14 where the cannula and theexpanded occluder have advanced beyond the end of the flange and intothe vessel and the cutting blade is retracted.

FIG. 15 shows a lateral cross-section of an embodiment having flangemounted on the cannula and a steering wire coupled to the distal end ofthe cannula where the occluder is in a collapsed condition.

FIG. 15A shows the embodiment of FIG. 15 where the steering wire hasbeen manipulated to curve the distal end of the cannula and the occluderis in an expanded condition.

FIG. 16 depicts a lateral cross-section of an embodiment having flangeand a hinged distal cannula region where the hinge is in a closedcondition and the occluder is in a collapsed condition.

FIG. 16A depicts the embodiment of FIG. 16 where the hinge is in an opencondition creating an infusion port, and the occluder is in an expandedcondition.

FIG. 17 is a lateral cross-section of an embodiment having a flange witha directional indicator, a cannula with three lumens, a cutting bladeand radiopaque marker bands, where the cannula is inserted through an 18French incision.

FIG. 18 is a top elevation of the embodiment of FIG. 17 showing thealignment of the directional indicator of the flange with the distalregion of the cannula.

FIG. 19 shows a lateral elevation of an embodiment with radiopaquemarker bands and an occluder asymmetrically disposed about the distalend of the cannula.

FIG. 19A shows the embodiment of FIG. 19 where the bottom region of theasymmetrically disposed occluder is preferentially expanding whencompared to the top region.

FIG. 20 shows the front view of the embodiment of FIG. 19, showing thepreferential expansion of the bottom region of the occluder as theoccluder goes from a collapsed condition to an expanded condition.

FIG. 21 shows an embodiment of an occluder that is an asymmetricpolyurethane balloon.

FIG. 22 is a lateral view of the embodiment of FIG. 21.

FIG. 23 shows an embodiment of an asymmetric occluder that is a balloonwith a thick region and a thin region where the asymmetric configurationof the balloon is shown in a collapsed condition, and when expanded, theballoon becomes symmetric.

FIG. 24 shows an embodiment of an symmetric occluder that is a balloonwith a higher shore region and a lower shore region where the symmetricconfiguration of the balloon is shown in a collapsed condition and, whenexpanded, the balloon becomes asymmetric.

FIG. 25 depicts an embodiment where the occluder is a balloon with wallsof varying thickness.

FIG. 26 depicts an embodiment with a three-lumen cannula having a curveddistal cannula region.

FIG. 27 is a front view of the embodiment of FIG. 26.

FIG. 28 is a lateral cross-section of the embodiment of FIG. 27 shownthrough section line 28—28.

FIG. 29 is a front view of the distal region of the cannula of theembodiment of FIG. 26 showing the closed distal end.

FIG. 30 is a top elevation of the embodiment of FIG. 29.

FIG. 31 a lateral view of the embodiment of FIG. 29 with a partialcross-section.

FIG. 32 is a bottom elevation of the embodiment of FIG. 29 showing theclosed distal end.

FIG. 33 is a back elevation of the embodiment of FIG. 29.

FIG. 34 is a lateral cross-section of the embodiment of FIG. 29 shownthrough section line 34—34.

FIG. 35 is an embodiment showing a self expanding occluder with aNitinol frame, a balloon seal and an impermeable membrane.

FIG. 36 shows an embodiment of a cannula poised to receive the occluderof FIG. 35.

FIG. 37 shows the occluder of FIG. 35 inserted through the side port ofthe cannula of FIG. 36.

FIG. 38 shows an embodiment of an occluder where the balloon has excessballoon material.

FIG. 39 shows a lateral cross-section of an embodiment of an occluderwhere the balloon is stored inside the distal end of the cannula whenthe balloon is in its collapsed condition and expands out the end of thecannula.

FIG. 40 shows a lateral cross-section of an embodiment of an occluderwhere the balloon includes an elastic line that is used to pull thecollapsed balloon back into the end of the cannula.

FIG. 41 shows a lateral cross-section of an embodiment of an occluderwhere the balloon is shown in a collapsed, partially expanded and fullyexpanded condition.

FIG. 42 depicts a lateral cross-section of an embodiment of an occluderwhere the balloon is an elastic material covered by a protective layer.

FIG. 43 depicts a lateral view of an embodiment of an occluder that is afunnel-shaped balloon expanding out the side of the distal end of thecannula.

FIG. 44 depicts a lateral cross-section of an embodiment having anoccluder aligner with a spring and an end sleeve shown with the occluderin a collapsed condition.

FIG. 44A depicts the embodiment of FIG. 44 with the occluder in anexpanded condition.

FIG. 45 shows the embodiment of FIG. 44 also having a cutting blade.

FIG. 46 shows a lateral cross-section an embodiment having a steeringwire and a flexible tube occluder aligner where the occluder is in acollapsed condition.

FIG. 46A shows the embodiment of FIG. 46 in an expanded condition wherethe steering wire has been manipulated to elevate the cannula tip.

FIG. 46B is an enlarged view of the distal end of the embodiment of FIG.46A.

FIG. 47 depicts a cardioplegia occluder positioned inside the aortaupstream from a blood cannula having a side channel housing a separatelyinsertable filter cannula, both upstream from a diverter.

FIG. 47A depicts a cardioplegia occluder having a separately insertablefilter cannula positioned inside the aorta upstream from a blood cannulawhich is upstream from a diverter.

FIG. 48 depicts a cardioplegia occluder which is upstream from a filtercannula which is upstream from a blood cannula which is upstream from adiverter.

FIG. 49 depicts a cardioplegia cannula that is upstream from anocclusion cannula, that is upstream from a filter, and which is upstreamfrom a diverter.

FIG. 50 depicts a cardioplegia occluder that is upstream from a filter,that is upstream from a blood cannula, and which is upstream from adiverter.

FIG. 51 depicts a cardioplegia occluder that is upstream from a filterand which is upstream from a diverter.

DETAILED DESCRIPTION

FIG. 1 depicts an embodiment of a cardioplegia occluder 1 for deliveringcardioplegia to the aorta during cardiopulmonary bypass where the distalregion 2 of the substantially rigid cannula 3 is curved to facilitateself-centering inside the aorta. The distal end of the cannula 14 isadapted to enter the aorta

In this embodiment, a spherical occluder 20 is circumferentiallydisposed about the outer surface 15 of the distal region of the cannulaforming a chamber 21 with an inner surface 22, an outer surface, aproximal end 24 and a distal end. In some embodiments, the occluder isan inflatable balloon. In other embodiments, the balloon is foam-filled,so that the occluder may be inserted in a contracted condition, forinstance, within a sleeve or under negative pressure, and when releasedfrom the sleeve or the negative pressure, will automatically expand tothe predetermined shape. Although FIG. 1 and FIG. 2 depict the occluderas spherical, in other embodiments, it is conical, elliptical or funnelshaped. In the embodiment of FIG. 1 and FIG. 2, the occluder is aninflatable balloon covering a portion of the curved distal region of thecannula. In certain embodiments, the occluder is circumferentiallydisposed about the distal region of the cannula so that the cannula runsthrough the longitudinal center axis of the occluder. In otherembodiments, the occluder is circumferentially disposed about the distalregion of the cannula so that the cannula runs through a regiondisplaced laterally from the longitudinal center axis of the occluder.For a detailed discussion of the construction of a balloon occluderdisposed on a cannula, the reader is referred to copending U.S.Applications Barbut et al., Ser. No. 08/645,762, filed May 14, 1996, andTsugita et al., Ser. No. 08/854,806, filed May 12, 1997, both expresslyincorporated herein by reference.

The cannula is typically a rigid or semi-rigid, preferably transparenttube having a proximal end adapted to receive cardioplegia solution anda cardioplegia lumen which extends distally from the proximal end andterminates and communicates with an infusion port in the distal regionfor delivery of cardioplegia solution to the aorta. The occluder, whichhas a longitudinal center axis, is mounted on the distal region of thecannula. The occluder is expandable between a contracted condition andan expanded condition, wherein the occluder, when contracted, is closelyassociated with the outer surface of the cannula, while the occluderexpands upon activation to substantially occlude the aorta downstream ofthe infusion port. During use, the occluder isolates the ascending aortafrom the peripheral vasculature without substantial migration of theoccluder into the ascending aorta. Because of the substantially rigidcondition of the cannula, the balloon may have a relatively smallfootprint where it is coupled to the distal region of the cannulawithout substantial migration of the occluder into the ascending aorta.

The embodiment shown in FIG. 1 and FIG. 2 has three lumens within thecannula. Other embodiments may have more or fewer lumens. In someembodiments, certain lumens are separate, non-communicating channels. Incertain embodiments, the lumens are generally substantially cylindrical,semi-rigid and preferably transparent. In FIG. 1 and FIG. 2, acardioplegia lumen 4 is adapted to receive cardioplegia through itsproximal end and deliver it to an infusion port 5 at its distal end. Theinfusion port 5 is proximal to the occluder, so that when the occluderis in an expanded condition, cardioplegia infuses to a region upstreamfrom the occluded aorta. Another lumen 7 is adapted to receive fluidthrough its proximal end and deliver it to an inflation port 8 at thedistal end of the lumen where it terminates and is in fluidcommunication with the chamber 21 of the occluder. When the occluder iscontracted, it is closely associated with the cannula's outer surface15. When fluid is delivered to the chamber of the occluder through theinflation port, the occluder expands away from the cannula, as depictedin FIG. 1 and FIG. 2. In one embodiment, the pressurized fluid used tofill the chamber of the occluder is saline solution and in anotherembodiment, it is gas. In another embodiment, negative pressure may beapplied to the lumen 7 to contract a foam-filled balloon. An aspirationlumen 10 has a proximal end 12 adapted to couple to an aspirator, andextends distally from the proximal end and terminates and communicateswith the infusion port 5. In embodiments having an aspiration lumen, theinfusion port can alternately deliver cardioplegia solution or aspirateembolic debris and other unwanted material from the aorta.

FIG. 3 and FIG. 4 depict another embodiment of the cardioplegia occluder1 where the distal end 16 of the cannula 10 is open forming a cuttingblade lumen to receive the cutting blade 30. The distal end 31 of thecutting blade, which when exposed, protrudes beyond the in the distalend of the cannula, has a sharpened tip 32 adapted to cut through thewall of the aorta. The embodiment shown in FIG. 3 and FIG. 4 includes aretractable blade guard 33 which is inserted into the distal end 16 ofthe cannula. The blade guard 33 is adapted to slideably receive thecutting blade 30. During use, the blade guard moves when pressed againstthe aorta to allow the blade to cut through the wall of the aorta, andthen the blade guard repositions to prevent the blade from cutting. Inthe embodiment shown in FIG. 3 and FIG. 4, the proximal end 34 of thecutting blade guard is coupled to the distal end of a spring 35. Theproximal end of the spring 36 is coupled to the inner surface of thecannula. When the spring is at its compressed length, as depicted inFIG. 3, the retractable blade guard is retracted exposing the cuttingblade 31. When the spring is at its extended length, the retractableblade guard covers the sharpened tip of the cutting blade as depicted inFIG. 4.

The cardioplegia occluder depicted in FIG. 3 and FIG. 4 is placed on theaorta, upstream from the brachiocephalic artery. When pressure isapplied to the cardioplegia occluder, the surface of the aorta pushes onthe retractable blade guard, compressing the spring and exposing thesharpened tip of the cutting blade which cuts through the wall of theaorta to create an incision for introduction of the distal end of thecannula. The distal end of the cannula, with the occluder in acontracted condition, is introduced through the incision made by thecutting blade. Such an embodiment can be introduced through a site thatis a maximum of 18 French. During insertion, aspiration can be effectedthrough the aspiration lumen to remove intravascular debris or airintroduced into the aorta during incision. The curved distal end of thecannula is positioned at the desired location inside the aorta, and theoccluder is expanded by introducing fluid through the lumen 7. Once theoccluder is fully expanded, blocking the blood supply to the aorta inthe region distal to the occluder, cardioplegia solution may beintroduced through the infusion port to the region upstream from theoccluder to stop the heart. Cardiac surgery, may then be performed.Alternately, negative pressure can be applied to the proximal end of theaspiration lumen to remove cardioplegia and embolic debris from theaorta. In embodiments that do not include a cutting blade, the incisionis made manually, and the distal end of the cannula is inserted aspreviously described. Following surgery, the flow of cardioplegiasolution is stopped, negative pressure is applied to the lumen, theoccluder contracts, the cardioplegia occluder is removed through theincision initially created for its insertion and the incision is closed.

FIG. 5 shows another embodiment where a blood cannula 56 has a channel57 located laterally that is adapted to receive a cardioplegia occluder58. When the occluder 20 is expanded inside the aorta 41, cardioplegiasolution can be delivered upstream of the occluder through the infusionport 59. This embodiment is one example of an integrated configurationof a blood cannula and a cardioplegia occluder for use in a “one-stick”application, meaning that only one incision need be made.

Human anatomy including the rib cage with deployed cardioplegia occluderis depicted in FIG. 6. The cardioplegia occluder 1 is disposed through achest access port 40 and thereafter enters the aorta 41 behind thesternum 45 at a location 42 upstream from the brachiocephalic artery 43.The rib cage is depicted generally by numeral 44. The cardioplegiaoccluder 1 is shown deployed within the aorta 41. The concept of portaccess allows a surgeon to enter the aorta via a port for a minimallyinvasive approach. By accessing the aorta directly, the device isdeployed without the need for visual guidance, e.g., fluoroscopy,echocardiography. This device would obviate the need for a sternotomyprocedure which is generally associated with conventional coronaryartery bypass grafting surgery.

The cardioplegia occluder may be constructed to sit in either directiononce introduced in the aorta by varying the location of the infusionport. In one embodiment, depicted in FIG. 7, an L-shaped cardioplegiaoccluder 1 is constructed to sit inside the aorta with occluder 20downstream from the incision site 55, with the occluder 20 mounteddistal to, or downstream from, the infusion ports 5. The cardioplegiaoccluder optionally includes seating bumps 50 to enhance sealing withthe interior of the aorta. In another embodiment shown in FIG. 7A, aJ-shaped cardioplegia occluder 1 is constructed to sit inside the aorta41 so that the occluder 20 is mounted proximal to, but still downstreamfrom, the infusion port 5 which is located at the distal opening 14 ofthe cannula. These cardioplegia occluders can be inserted through apre-slit section of the aorta, or a cutting blade can be mounted on thedistal end of the cannula and advanced through the aortic wall.

The cannula utilizes a rigid preformed material with multiple lumens andan occluder, typically a balloon occluder. The intent of the rigidcannula is to provide device control and stability during placement andusage. Eliminating the floppy characteristics associated withcatheters/cannulae constructed of soft rubbery plastics is vital toenabling the user to establish and maintain precise deployment locationof the device (balloon). With a stiff or substantially rigid cannulatube, or in an alternate embodiment, a cannula with a stiff orsubstantially rigid distal region, the occlusion balloon is effectivelylocked into position thus limiting movement (i.e., migration) even whenthe device (balloon) is exposed to external forces (i.e., systemic bloodpressure and jetting force from fluid infusion, and particularly thepressure differential that develops across an occlusive device). Theterm “distal region” described above as stiff or substantially rigidpreferably means that region of the cannula that lies distal to thebodily incision through which the cannula is inserted when the cannulais properly positioned for use. In embodiments with flanges, the term“distal region” preferably means that region of the cannula that liesdistal to the flange. The region proximal to the distal region is alsosubstantially rigid in some embodiments and is soft and non-rigid inother embodiments. In some embodiments, the substantially rigid distalregion can extend one centimeter proximal to the flange or bodilyincision when the cannula is in use, 2 centimeters proximal to theflange or bodily incision, 3 centimeters proximal to the flange orbodily incision, 4 centimeters proximal to the flange or bodilyincision, 5 centimeters proximal to the flange or bodily incision, or 6centimeters proximal to the flange or bodily incision or any otherdistance up to and including the proximal end of the cannula.

Hardness properties of plastic materials are typically characterizedusing indentation devices (durometers). See ASTM D2240-97, incorporatedherein by reference. There are several durometer ranges (i.e., A, B, C,D, etc.) which are used to characterize plastic materials. Each range isdefined by specific test parameters. The most common ranges for plasticsare Type A (aka Shore A) and Type D (aka Shore D). As the durometernumber decreases, the hardness of the material becomes lower (softer)for both ranges. Shore A durometer measurements are usually used todescribe softer plastics than the Shore D durometer measurements.However, the two ranges overlap on a large portion of their measurementrange. See Table A: Durometer Scale Comparison Chart from ASTM D2240-97,incorporated herein by reference.

Nasu U.S. Pat. No. 5,425,708 (Nasu '708) referenced soft polyvinylchloride (PVC), polyurethane rubber, and silicone rubber as materialsthat could be used to construct the cannula tubing. Each of thesematerials is commercially available in a wide range of hardness.However, typical hardness range for these soft/flexible material is 10to 75 Shore A (see page 68, Industrial Plastics, Richardson 1983,incorporated herein by reference), but can get as high as 89 Shore A insome instances. Silicone rubber is commonly available (unreinforced) inthe 10 to 70 Shore A range.

By contrast, the rigid or substantially rigid cannula of the presentinvention is constructed from various rigid materials, metal andnon-metal. Materials disclosed herein for use in the rigid orsubstantially rigid cannula also apply to embodiments where only thedistal region of the cannula is rigid or substantially rigid. Devicesmay be made with stainless steel, polycarbonate, nitinol, ceramics, orother plastics like polyurethane and PEBAX (polyether block amides),PVC, polyolefin, polystyrene, nylon, polyimide, and plastic with metalreinforcement (braiding). The rigid cannula tube is made preferably frommaterials with hardness of at least 90 Shore A. More preferably,materials with a hardness greater than 90 Shore A, more preferably 91Shore A, more preferably 92 Shore A, more preferably 93 Shore A and morepreferably 94 Shore A are used and most preferably, materials with ahardness of 95 Shore A and above are used. While materials in the rangeof 90 shore A and above are generally measured on a Shore D durometer,these materials are described here in Shore A measurements so that theymay be more readily compared with the softer plastics of the relatedart, which are typically measured on Shore A durometers.

Certain embodiments of the rigid cannula include plastic materials thatmay register hardness as high as 100 Shore D. As for reinforced plasticmaterials, softer plastic material can be used with metal braiding toprovide additional rigidity. Any stainless steel and nitinol can also beused. See Table A, page 81 of Industrial Plastics, Richardson 1983,incorporated herein by reference.

Related art devices, such as those described in Nasu '708, specifiedthat the L-shaped or curved distal end be “made of soft plastic . . . ”(Nasu '708, Col. 3, lines 27-28). Since the L-shaped distal end of thecannula must be temporarily straightened to insert it into the vessel,soft plastics were apparently thought to have specific advantages. Forinstance, it is widely accepted by those skilled in the art that softplastics can be temporarily deformed or straightened and will resumetheir approximate original shape without “kinking” or otherwise showingpermanent deformation. On the other hand, rigid plastics can be bent,but not straightened without structural deformation.

However, the soft materials tended to deform or flex both upon insertionand once positioned in the vessel, thus creating insertion and migrationproblems. The present invention solves this problem by using a cannulawith a substantially rigid distal region that eliminates uncontrolledflexing during insertion and once in position in the vessel. The segmentof substantial rigidity may extend proximal from the distal end by up to2 cm, up to 3 cm, up to 4 cm, up to 5 cm, or up to 6 cm. In anotherembodiment, the entire cannula is substantially rigid. Thus the devicemay be introduced without additional support such as mandrels, styletsand introducers. Moreover, the rigidity of the device stabilizes it oncein the vessel, thus restricting movement of the cannula in the vesseldue to environmental (blood/fluid pressure) forces.

It is also to be noted that the Nasu '708 patent calls for cannula tubesizes ranging from 10-13 mm outer diameter (OD) and greater than 7 mminner diameter (ID). See Nasu '708 Col. 3, lines 30-31 and lines 36-37,respectively. This range of diameters far exceeds the usable diameterrange for a cardioplegia balloon cannula. Cardioplegia balloon cannulas,such as those of the present invention, typically have a maximum OD of 6mm (18 French) and preferably a maximum OD of 5.3 mm (16 French).

An integrated, multiple component port access cardioplegia occluder isdepicted in FIG. 8. The system includes a cutting blade 60 having apre-shaped configuration 61, a sharp tip 62, and position limiters 63.The cannula 3 includes a suture plate 70, a kink-resistant shaft 71, anopening 72 to receive cardioplegia infusion solution into thecardioplegia lumen and a hemostasis valve 73. The balloon cannula 80includes an occluder 81, an inflation port 82 and a lumen 83 and isadapted to receive a filter mesh 500 through the lumen. The cannula 3 isadapted to receive the cutting blade 60 through the infusion port 72,and to receive the occlusion device 80 through the hemostasis valve 73.In use, a port access point or window is opened on the patient's chest.Tissue from the port to the aorta is dissected. The cutting blade andcannula are advanced through the aortic wall. A purse string suture(s)may be required to aid in wound closure and to secure the device. At thedesired location, the cutting blade is advanced through the aortic walland the cannula is pushed with the cutting blade. Once inside thevessel, the cannula is secured and the cutting blade is removed. At thispoint, the occluder (and any filter) may be advanced and expanded.Cardioplegia and other fluids may then be circulated through thecardioplegia lumen.

The distal end of the cannula may assume various designs to assist thesurgeon in positioning the cardioplegia occluder in the aorta. In oneembodiment, depicted in FIG. 9, a lumen 90 is adapted to receive thecutting blade 110. The cutting blade lumen 90 enters the distal regionof the cannula 3 at an angle. A substantially straight cutting blade 110is introduced into the lumen 90 so that the sharp tip 111 of the bladeprotrudes beyond the opening 91 at the distal end of the cutting bladelumen. In use, this embodiment allows for a single stick motion wherebythe cutting blade pierces the wall of the aorta creating an incision andthe distal end of the cannula, with the occluder in a collapsedcondition, is advanced through the incision. A flange 100 mounted on thecannula presses against the exterior surface of the aortic wallpreventing further movement of the cannula into the vessel at the pointwhere the cannula is positioned in the desired location within theaorta. The cutting blade is then retracted and the occluder 20 isexpanded to block the flow of arterial blood. An advantage of thisembodiment is that it has no moving parts other than the retractablecutting blade. In other embodiments, the cutting blade lumen extendsdistally from the proximal end of the cannula.

The embodiment depicted in FIG. 10 has a retractable cutting blade 112slideably inserted into a cutting blade lumen 92 within the distal endof the cannula 3. The proximal end 114 of the cutting blade is coupledto a spring 120 and to an activator line 130. The activator line can bemade of material such as wire. The proximal end of the spring is coupledto a stop 121 formed inside the cutting blade lumen. When the activatorline 130 is pulled, the spring 120 compresses and the sharp tip 111 ofthe cutting blade 112 is retracted into the distal end of the cuttingblade lumen 92 which then serves as a blade guard. When the activatorline 130 is released, the spring 120 expands and the sharp tip 111 ofthe device is exposed to allow incision into a vessel. The embodimentalso includes infusion ports 101 for introduction of cardioplegiasolution upstream from the occluder 20.

FIG. 10A shows another embodiment where the blade guard is a retractableobturator 140. In this embodiment, the distal end 114 of the cannula issharp, thus forming the cutting blade, and is used to create the initialincision into the aorta. The retractable obturator 140 is slideablyreceived through the cutting blade. In the embodiment of FIG. 10A, theretractable obturator is coupled on its proximal end to a spring 120 andto an activator line 130. The spring is coupled on its proximal end to astop 121 formed inside the cutting blade lumen. During use, theobturator can be moved by pulling on the activator line to expose thesharp distal end 114 of the cannula which is used to cut through thewall of the aorta. When the activator line is released, the obturatormoves back to prevent the blade from cutting.

FIG. 11 depicts a flange sleeve 105 adapted to receive the cannula. Insome embodiments, the flange sleeve is substantially cylindrical. Inother embodiments, the flange sleeve may have a different shape oncross-section such as square, rectangular, oblong or other shapes. Theflange sleeve has a sharpened distal end 116 adapted to cut through thewall of the aorta, an inner surface 108, an outer surface 109, aproximal end 117, a distal end and a longitudinal center axis. The lumen118 of the flange sleeve 106 runs along the longitudinal center axis andcommunicates with openings at the proximal 117 and distal 116 ends ofthe sleeve. This embodiment also includes a flange stop 107, with a topsurface 125, which faces the proximal end of the flange sleeve, and abottom surface 126, which faces the distal end 116 of the flange sleeve.The flange stop 107 is mounted on the flange sleeve. The perimeter ofthe flange stop can be substantially circular, or shaped so that aregion of the perimeter includes a protrusion or notch in the plane ofthe flange stop, where the protrusion or notch indicates the directionof the tip 128 of the cutting edge 116 of the flange sleeve. In theembodiment of FIG. 11, the portion of the flange sleeve distal to thebottom surface 126 of the flange stop 125 and proximal to the cuttingedge 116 at the distal end of the sleeve is of a length 119 that willposition the cutting edge 116 of the flange sleeve at a predetermineddepth inside the aorta when the bottom surface 126 of the flange stopcontacts the outer surface 46 of the aorta thus preventing furthermovement of the flange sleeve into the aorta. FIG. 11 shows the cannula3 retracted inside the lumen of the flange sleeve. When in the retractedstate, the occluder 20 is in a contracted condition. When in use, thecutting edge 116 of the flange sleeve is pressed into the outer surfaceof the wall of the aorta 46, while the cannula 3 is in the retractedstate and the occluder 20 is in a contracted condition. The cutting edge116 of the flange 105 is advanced into the aorta until the flange stop107 contacts the outer surface of the wall of the aorta 46. In the nextstep, as depicted in FIG. 12, the cannula 3 is advanced beyond thecutting edge 116 of the flange until the distal end of the cannula issituated at the predetermined position within the aorta 41. The occluder20 is then expanded to prevent blood flow downstream in the aorta. Inthis embodiment, the distal end of the cannula is semi-rigid andpreformed to assume a substantially curved condition when released fromthe flange. When retracted inside the flange, as depicted in FIG. 11A,the semi-rigid distal end of the cannula 3 generally conforms to theshape of the flange sleeve lumen which is straight.

In another embodiment, depicted in FIG. 13, the flange 105 includes aflange sleeve 106 with an inner surface 108, an outer surface 109, aproximal end 117, a distal end 129, and a longitudinal center axis. Thelumen 118 of the flange sleeve 106 runs along the longitudinal centeraxis and communicates with openings at the proximal 117 and distal 129ends of the sleeve. This embodiment also includes a substantially flatflange stop 107, with a top surface 125, which faces the proximal end ofthe flange sleeve, and a bottom surface 126 which is flush with thedistal end 129 of the flange sleeve. The bottom surface 126 of theflange stop is adapted to press against the outer surface 46 of theaorta. FIG. 13 also shows the cannula 3 partially retracted inside thelumen 118 of the flange sleeve. When in the retracted state, theoccluder 20, which is disposed about the distal region of the cannula 3,is in a contracted condition. In this embodiment, the distal end 145 ofthe cannula includes a cutting blade lumen having a retractable cuttingblade 146 with a sharpened cutting edge 147 at its distal end. Thecutting blade 146 slideably inserts inside the cutting blade lumen andprotrudes beyond the distal end 145 of the cannula 3. When in use, theflange 105 is positioned with the bottom surface 126 of the flange stop107 pressing against the outer surface of the wall 46 of the aorta andthe cannula 3 and cutting blade 146 are in the retracted state insidethe lumen 118 of the flange sleeve 106 proximal to the distal opening129 of the sleeve. The cannula 3 and the cutting blade 146 are pushedthrough the lumen 118 of the flange sleeve beyond the distal opening 129so that the sharpened cutting edge 147 of the cutting blade 146 cutsinto the wall of the aorta forming an incision as depicted in FIG. 13.Once the incision is formed, the cannula 3 is advanced beyond the distalopening 129 of the flange sleeve 106, as depicted in FIG. 13A, so thatthe distal end of the cannula and the occluder 20 are introduced intothe aorta 41 to the predetermined depth and position. In thisembodiment, the semi-rigid distal end of the cannula is preformed toassume a curved shape once it is released from the lumen of the flange.As the cannula is advanced beyond the distal opening 129 of the flangeinto the aorta, the cutting blade 146 slideably retracts within thecannula so that is does not protrude beyond the distal opening 146 ofthe cannula. Once the cutting blade has been deployed to create theinitial incision, it is desirable to retract it inside the cannula orotherwise guard the sharpened tip so that the sharp edge of the bladedoes not scrape or cut the inner surface 47 of the wall of the aortaopposite the incision site. The occluder 20 may then be expanded toocclude arterial flow downstream in the aorta.

In another embodiment, depicted in FIG. 14, the flange 105 includes aflange sleeve 106 with a proximal end 117, a distal end 129, and alongitudinal center axis. The lumen 118 of the flange sleeve 106 runsalong the longitudinal center axis and communicates with openings at theproximal 117 and distal 129 ends of the sleeve. This embodiment alsoincludes a substantially flat tear-away flange stop 150, with a topsurface 151, which faces the proximal end of the flange sleeve, and abottom surface 152, which is flush with the distal end 129 of the flangesleeve. The tear-away flange stop 150 is disposed about the outersurface of the flange sleeve 106 at the distal end 129 of the sleeve.The bottom surface 152 of the tear-away flange stop is adapted to pressagainst the outer surface 46 of the aorta to limit the initial insertiondepth into a vessel. FIG. 14 also shows the cannula 3 partiallyretracted inside the lumen 118 of the flange sleeve. When in theretracted state, the occluder 20 is in a contracted condition. A cuttingblade 160 is adapted to slideably insert inside a lumen within thecannula. In this embodiment, the distal end 161 of the cutting blade issharpened 161 to cut through the wall of the aorta. When in use, thecannula 3, with the sharpened cutting edge 161 of the cannula insertiondevice 160 exposed, is advanced through the wall of the aorta until thebottom surface 152 of the tear-away flange stop 150 presses against theouter surface of the wall of the aorta. As depicted in FIG. 14A, thecutting blade 160 is then retracted within the distal end of the cannula3 as the tear-away flange is removed and the cannula is advanced intothe lumen of the aorta until the bottom surface 126 of the permanentflange stop 107 presses against the outer surface 46 of the wall of theaorta. By this process, the distal end of the cannula and the occluder20 are introduced into the aorta 41 to the desired depth and position.In this embodiment, the semi-rigid distal end of the cannula ispreformed to assume a curved shape once it is released from the lumen ofthe flange. The occluder 20 may then be expanded to occlude arterialflow downstream in the aorta.

As described previously, in certain embodiments, the distal region ofthe cannula may be preformed to a desired shape to allow the cannula tobe positioned at the desired depth and orientation within the aorta. Inother embodiments, the distal region of the cannula may be mechanicallyactivated by an occluder aligner to allow proper positioning of theoccluder within the aorta. FIG. 15 depicts an embodiment with one formof occluder aligner that includes a cannula 3 with an inner surface 170,an outer surface 171, a proximal end (not shown), a distal end 145 and alongitudinal center axis. The lumen 172 of the cannula runs along thelongitudinal center axis and communicates with openings at the proximaland distal 145 ends of the cannula. The cannula also includes a flangestop 107 disposed about the outer surface 171 of the distal region ofthe cannula. The occluder aligner of this embodiment includes a steeringwire 130 carried by the cannula, displaced from the center axis of thecannula and attached on a first end 131 in the distal region of thecannula, in the case of this embodiment, to the inner surface 170 of thedistal region. When in use, as depicted in FIG. 15 and FIG. 15A, thecardioplegia occluder 1 is advanced through an incision in the wall ofthe aorta 41 until the bottom surface 126 of the flange stop 107 pressesagainst the external surface of the wall 46 of the aorta. At this point,as shown in FIG. 15, the occluder 20 is in a contracted condition. Thesteering wire 130 is then manipulated, as depicted in FIG. 15A, to movethe distal end of the cannula into a curved condition, so that thedistal opening 145 of the cannula points downstream within the aorta 41.In one embodiment, the occluder is aligned by pulling on the steeringwire. In another embodiment, the steering wire is fabricated from amaterial that shortens upon application of a predetermined electricalinput. When this predetermined electrical input is applied to thesteering wire, the wire shortens by a predetermined length, pulling thedistal end of the cannula into the predetermined position. In anotherembodiment, a control circuit containing a memory storage devicecontrols the electrical input to be applied and the timing of theapplication and discontinuance of the electrical input, so that thechange in length of the wire may be programmed. Once the occluder 20 isproperly aligned within the aorta, the occluder may be expanded toocclude arterial flow downstream in the aorta.

FIG. 16 depicts another cannula that is mechanically activated tofacilitate proper positioning of the occluder within the aorta. Thisembodiment includes a cannula 3 with an inner surface 170, an outersurface 171 and a longitudinal axis. The cannula is divided into twosegments, a proximal portion 185 and a distal portion 186, flexiblycoupled to one another. In the embodiment shown in FIG. 16, the flexiblecoupling is a hinge 180. In the closed condition, as depicted in FIG.16, the distal end of the proximal portion 185 and the proximal end ofthe distal portion 186 align at a circumferential region 181, so thatthe cannula assumes a substantially cylindrical shape. In otherembodiments, the cannula on cross-section can be rectangular, square,oblong or other shapes. In the open condition, as depicted in FIG. 16A,the distal portion 186 rotates about the hinge so that the longitudinalaxis 188 of the distal portion 186 is about a 90° angle to thelongitudinal axis 187 of the proximal portion 185. In the closedcondition, the lumen 172 of the cannula runs along the longitudinalcenter axis and communicates with openings at the proximal and distal145 ends of the cannula. The cannula also includes a flange stop 107disposed about the outer surface 171 of the distal region of thecannula, and a cutting blade 160 which slideably inserts within thelumen 172 of the cannula when the cannula is in the closed condition.When in use, as depicted in FIG. 16, the cutting blade 160 protrudesbeyond the distal end 145 of the cannula 3 which is in the closedcondition with the occluder contracted. The presence of the cuttingblade in the lumen of the cannula helps maintain the cannula in a closedposition. The sharp distal end 161 of the cutting blade 160 is advancedthrough the wall of the aorta 41 creating an incision, and the cannula 3is advanced into the aorta until the bottom surface 126 of the flangestop 107 presses against the external surface of the wall 46 of theaorta. The cannula insertion device is then removed causing the hinge toopen as depicted in FIG. 16A, and the cannula assumes the open conditionwith the distal portion 186 of the cannula pointing downstream in theaorta. In some embodiments (not shown), the cannula opens with theassistance of a spring-loaded hinge. The occluder 20 may then beexpanded to occlude arterial flow downstream in the aorta. Cardioplegiasolution may then be introduced through the proximal portion 185 of thecannula for delivery through the fluid port 189 upstream of theoccluder.

FIG. 17 depicts an embodiment where the distal region of the cannula 3is tapered 210. The embodiment of FIG. 17 also shows, a curved region212, distal to the tapered region. In this embodiment, the taperedregion, on cross-section, as depicted in FIG. 18, is substantiallyelliptical. As also depicted in FIG. 18 from a top elevation, the longdiameter of the ellipse of the tapered region cross-section liesdirectly above the curved region 212 of the cannula. This embodimentalso includes a flange which is slideably received by the cannula. Theflange in this embodiment has a directional indicator. As can be seen inthe top elevation of FIG. 18, the flange assumes the shape of a polygon.In other embodiments, the flange can be other shapes such asrectangular, oblong, or triangular. The flange includes a hole 204 thatis substantially elliptical, having an inner circumference 202. The holeis placed off-axis from the center of the polygon. The long diameter ofthe elliptical hole is perpendicular to the directional edge 203 of thepolygon perimeter of the flange. The distance from the directional edge203 to the nearest point on the inner circumference of the hole 204 isgreater than the distance from the edge 201 opposite the directionaledge to the point on the inner circumference nearest that opposite edge.The inner circumference 202 of the hole in the flange is greater thanthe circumference of the outer surface 211 of the distal end of thetapered region 210 of the cannula, but less than the circumference ofthe outer surface 211 of the proximal end of the tapered region 210 ofthe cannula. The flange is disposed about the tapered region of thecannula. The distal end of the tapered region is adapted to slideablyinsert in the hole of the flange and the proximal portion of the taperedregion slideably inserts in the flange up to the location where thecircumference of the outer surface 211 of the tapered region of thecannula is substantially equal to the inner circumference 202 of thehole in the flange, at which location the flange is no longerfree-floating, and locks into position on the tapered region. Thetapered condition of the cannula assists in sealing the cannula to theflange. Since the hole 204 of the flange and the cross-section of thetapered region are both elliptical in shape, the flange will always beoriented in the same position on the cannula when it locks into place;that is, the directional edge 203 will always point toward the curvedregion 212 of the cannula, which assists the surgeon in knowing whichway the occluder is pointing in the aorta. In other embodiments, thetapered region 210 and the hole 204 of the flange may assume othershapes on cross-section, such as rectangular or triangular. In someembodiments, the directional edge is identified by a specific color. Theembodiment of FIG. 17 also includes marker bands 220 around the outersurface 211 of the curved region 212 of the cannula in the most proximaland most distal locations where the occluder 20 contacts the cannula.The marker bands are made of radiopaque material such as metal-polymericalloy so that the surgeon can identify the position of the occluder.

For the cardioplegia occluder to function properly, the occluder must beadapted to occlude aortas of varying diameters. Moreover, the internalsurface of the aorta may have varying surface features creatingadditional challenges to fashioning occluders that will conform to thetopography of the inner surface of the vessel and form a complete seal.The challenge of occluding aortas of varying diameter is furthercompounded in embodiments with fixed flanges. To overcome suchobstacles, in certain embodiments, the occluder is a balloon having afirst region of first expansion capacity and a second region of secondexpansion capacity where the first expansion capacity is greater thanthe second expansion capacity. During use, the second region expandspreferentially and to a greater extent than the first region. Theseembodiments can thus compensate for insertions where the distal end ofthe cannula does not lie directly in the center of the aorta and by thuscompensating creates effective sealing. In some embodiments, the varyingexpansion capacity is created by forming the first region from aflexible material of different thickness that the flexible material usedto create the second region. In other embodiments, the first region isof a different elastic modulus or durometer hardness than the secondregion. In other embodiments, the occluder is adapted to occlude aortasof varying diameters by asymmetrically mounting the balloon on thedistal region of the cannula. The embodiment shown in FIG. 19, whichdemonstrates this last case, has an occluder 20 that is a preformedasymmetric balloon where the “long” side 230 has less capacity to expandthan does the “short” side 231. The flange 107, as described in previousembodiments, will hold the curved portion 212 of the cannula at apredetermined distance below the region of the wall of the aorta closestto the flange. In aortas of varying diameters, the distance between thecurved portion of the cannula and the wall opposite the flange willnecessarily vary. To facilitate occlusion in these varying conditions,the short side 231 has a greater capacity for expansion, as depicted inFIG. 19A, than does the long side 230, so that upon inflation by acommon fluid source, the short side 231 will preferentially expand overthe long side 230. FIG. 20 is a front elevation of the embodiment ofFIG. 19A showing how the short side 231 preferentially expands over thelong side 230 to occlude aortas of smaller 240, intermediate 241, andlarger 242 diameters even though the flange 107 fixes the depth of thecannula within each vessel.

There are several methods to achieve varying capacities for expansion ingiven regions of the balloon occluder. Typically, it is desired toachieve a preferential expansion zone as depicted in FIG. 21 where aballoon occluder 20 is asymmetrically disposed about a cannula, and theoccluder has a region 251 that has a greater capacity to expand whencompared to another region 250. FIG. 22 is a lateral elevation of theembodiment of FIG. 21. These asymmetric balloons, which can befabricated from polyurethane, typically inflate to a more symmetricshape as depicted in FIG. 23, where varying balloon wall thickness isused to control expansion characteristics. A thin region 252 of theballoon will expand first, reaching a certain level of strain/elongation252′, then a thicker region 253 will stretch to its expanded condition253′. The expanded balloon is symmetrically disposed about the cannula.

FIG. 24 depicts another embodiment where balloon materials withdiffering expansion capacities are used to create a balloon which isasymmetric upon expansion. In this embodiment, a region of soft material255, e.g., one of lower modulus and usually lower durometer, expandsmore freely 255′ than does a region of harder material 254, e.g., one ofhigher modulus and usually higher durometer, which expands less freely254′.

It is also important that the occluder not prolapse at the locationswhere the occluder surface is not in contact with the inner surface ofthe aorta when the occluder is expanded. Such prolapse can cause theoccluder to not seal properly. Increasing thickness in these non-contactregions can reduce the risk of prolapse and can otherwise controloccluder length and shape. FIG. 25 depicts an embodiment where theballoon occluder has regions where the balloon material is thin 256 andsidewall regions where the balloon material is thick 257. When theballoon expands, the thin regions 256, which ultimately contact theinner wall of the aorta, expand more freely to their expanded condition256′. The thick sidewall regions 257, which do not contact the innersurface of the aorta and are thus at risk of prolapse, expand lessfreely to their expanded condition 257′ and, due to their thickness, aremore robust. The overall average balloon length from location 260 tolocation 261 is reduced from the length that would otherwise result ifthe sidewalls were not made of thicker material. Thus, aprolapse-resistant balloon occluder with a small “footprint” (area ofcontact on the distal region of the catheter), can be fabricated. Thissmall footprint occluder, when used with the substantially rigid cannulaallows the occluder to isolate the ascending aorta from peripheralvasculature without substantial migration of the occluder into theascending aorta.

FIG. 26 depicts an embodiment of a cardioplegia occluder 1 where thesubstantially rigid cannula 3 includes three lumens 4, 10 and 7, aflange 107 and a spherical occluder 20. The infusion port 5 is shownproximal to the occluder. Certain embodiments of the cannula are made ofclear polycarbonate acrylic, ABS or stainless steel. In one embodiment,the region of the cannula proximal to the flange is made of clearpolycarbonate, acrylic or ABS, and the region of the cannula distal tothe flange is made of stainless steel. The plastic region and thestainless steel region are insert-molded at the junction. In thepreferred embodiment, (i) the length of the cannula from the proximalend to curved portion of the distal region is in the range of 5-10inches, most preferably 7.5 inches, (ii) the width of the distal regionfrom the beginning of the point of curvature to the distal end (distanceA in FIG. 26) is in the range of 0.25-0.75 inches, most preferably0.45-0.50 inches; and (iii) the distance between the flange and thedistal end (distance B in FIG. 26) is the range of ⅜ inch to 1.0 inch,and most preferably ¾ inch. FIG. 27 is a front elevation of theembodiment of FIG. 26. FIG. 28 is a lateral cross-section of theembodiment of FIG. 27 shown through section line 28—28. Here, thepathways of the three lumens are depicted in greater detail. The lumen 7is shown communicating with the inflation port 8 which opens into thechamber of the occluder 20. The cardioplegia lumen 4 is showncommunicating with the infusion port 5 which opens into the region ofthe aorta upstream of the occluder. The aspiration lumen 10 alsocommunicates with the infusion port. FIG. 29 is a front elevation of thedistal region of the cannula 3 of the embodiment of FIG. 26 with theoccluder removed. In this figure, the closed distal end 14 of thecannula can be seen. FIG. 30 is a top elevation of the embodiment ofFIG. 29, showing the relative locations of the lumen 7 that is used toinflate/deflate the occluder, the cardioplegia lumen 4 and theaspiration lumen 10 as they enter the region of the cannula justproximal to the flange. FIG. 31 is a lateral view of the embodiment ofFIG. 29 with a partial cross-section of the curved region of thecannula. The occluder mounting zones 270 are shown on either side of thecross-section region. This view shows the relationship between theinfusion port 5, shown proximal to the occluder mounting zones, and theinflation port 8 which opens in the region between the occluder mountingzones and thus communicates with the chamber of the occluder. FIG. 32 isa bottom elevation of the embodiment of FIG. 29. FIG. 33 is a backelevation of the embodiment of FIG. 29, again showing the relativelocations of the infusion port 5 and the inflation port 8. FIG. 34 is alateral cross-section of the embodiment of FIG. 29 shown through thesection line 34—34.

FIG. 35 is an embodiment showing a self-expanding occluder 320 with ahollow Nitinol frame 300, a balloon seal 301 and a fluid-impermeablemembrane 302. The occluder is an annular-shaped balloon having an innercircumference and an outer surface and a flexible, fluid-impermeablemembrane bonded to the outer surface of the balloon and covering thearea circumscribed by the inner circumference of the annular balloon.FIG. 36 shows a cannula 3 with an occluder side port 310, a flange stop107 and a fluid port 311. FIG. 37 shows the self-expanding occluder 320,which has been inserted into the occluder side port 310 while in acollapsed condition after the distal region of the cannula has beeninserted into the aorta 41. Once properly positioned, the balloon seal301 is inflated through the hollow Nitinol frame 300 and the occluderexpands, occluding the vessel.

In some applications it is desirable to provide occluder constructionswith enhanced stability and/or increased expandability. FIG. 38 depictsan overlapping balloon occluder 321, fabricated with excess balloonmaterial, which allows the occluder to inflate to a larger size whilestretching and elongating to a lesser extent. A portion of the occluderin its expanded condition 321′ is also shown. This embodiment may alsoinclude thicker regions of the balloon wall to control the inflationprofile.

In certain embodiments, the cannula is open at the distal end and thedistal end has a lumen where the occluder, when contracted, is stored asshown in FIG. 39. This figure depicts an expanding balloon occluder 322.Upon expansion, the balloon advances out of the distal end of thecannula. As the balloon is inflated, more balloon material is availableto expand, thus permitting occlusion of larger sized vessels once theballoon reaches its expanded condition 322′.

FIG. 40 and FIG. 41 depict a cannula with an open distal end for storageof a contracted balloon occluder 323. The balloon can be retracted upondeflation into the distal end 14 of the cannula 3 by pulling on anelastic line 330 which passes through the lumen of the cannula. Theelastic line 330 is coupled to the proximal end 331 of the balloon andthe distal end 332 of the balloon, so that when the balloon is fullyexpanded 323″, the elastic line is fully stretched. Upon deflation, theelastic line contracts and the distal end 331 of the balloon movescloser to the proximal end 332 of the balloon. The deflated balloon 332may then be pulled into the distal end 14 of the cannula by pulling onthe elastic line 330. FIG. 41 depicts the balloon in its initialcontracted condition 323, a deflated condition 323′ and a fully expandedcondition 323″, where the elastic line is not shown.

In some applications it may be advantageous to cover the occluder with aprotective layer. FIG. 42 shows a balloon occluder 20 disposed about thedistal end of a cannula 3. The balloon 325 itself is made of an elasticmaterial and its outer surface is covered by a protective material 326.In some embodiments, the protective layer itself has elastic capacity.In other embodiments, the protective layer is internal to the balloon sothat the external surface of the protective layer is covered by theballoon material.

FIG. 43 depicts an embodiment where a funnel-shaped occluder 328 made ofelastic material is deployed through a side opening 340 of the cannula3. The funnel-shaped occluder 328 can occlude vessels of varying sizesdue to its shape.

Occluder aligners, which were described previously for manually aligningthe distal end of the cannula, can also be used to provide positionstability to expanding occluders. In some applications, an expandingoccluder will “rock” out of position during expansion if the distalregion of the cannula is not positioned along the center longitudinalaxis of the aorta. Certain embodiments therefore include cannulas withoccluder aligners of various designs to stabilize the position of theoccluder and distal cannula during occluder inflation. One embodimentincludes a longitudinally deformable region and an end sleeve whichslides relative to the distal end of the cannula and is coupled to thelongitudinally deformable region and to the occluder. During use, theoccluder expands and the end sleeve moves proximally, therebycompressing the longitudinally deformable region. FIG. 44 and 44Ademonstrate this embodiment, where the longitudinally deformable regionis a spring. FIG. 44 shows the distal region of the cardioplegiaoccluder 1 where the occluder 20 is in the collapsed condition. Thespring 400 is coiled about the distal region 401 of the cannula insidethe occluder chamber. The proximal end 402 of the spring is coupled tothe region of the cannula inside the occluder chamber just distal to theproximal end of the occluder 403. The end sleeve 404 is disposed aboutthe distal region of the cannula. The proximal end 405 of the end sleeveis coupled to the distal end of the spring 400. The end sleeve 400 iscoupled to the distal end of the occluder in a region 406 of the endsleeve just distal to the proximal end of the sleeve. The end sleeveincludes a seal 407 near the distal end of the sleeve adapted tosurround the distal region of the cannula 3 so that this distal cannularegion slideably inserts in the seal. The seal is adapted to preventfluid in the occluder chamber from escaping from the occluder. In thisembodiment, the occluder aligner includes an end stop 408 to prevent theend sleeve from sliding off the distal end of the cannula 3 during use.FIG. 44 also shows the location of the inflation port 8 inside theoccluder chamber. FIG. 44A shows the embodiment of FIG. 44 where theoccluder is in the expanded condition and the proximal end 405 of theend sleeve has moved along the distal region 401 of the cannula towardthe proximal end of the occluder 403 and the spring 400 has compressed.

FIG. 45 depicts an embodiment of a cardioplegia occluder 1 that includesan occluder aligner where the distal end of the end sleeve 404 of theoccluder aligner is a sharpened edge 420 that serves as a cutting blade.In use, the sharpened edge 420 creates the initial incision into theaorta and the cannula with the collapsed occluder is advanced into thelumen of the vessel. The occluder is expanded and the end sleeve 406slides proximally along the distal region 401 of the cannula retractingthe sharpened edge 420. In this embodiment, the longitudinallydeformable region of the occluder aligner is a flexible tube.

An occluder aligner with a steering sleeve slideably mounted on thecannula and coupled to a steering wire is depicted in FIG. 46. In thisembodiment, the steering sleeve 455 is disposed about the region of thecannula 3 proximal to the occluder 20, so that the cannula slideablyinserts in the steering sleeve. The distal end 453 of the steering wireis coupled to the inner surface of the distal region of the cannula inthe area where the occluder is coupled to the cannula. The steering wire454 is carried by the cannula and is displaced from the longitudinalcenter of the cannula. In some embodiments, the steering wire passesthrough a hole or slot in the cannula which is distal to the region ofthe cannula which is inserted into the vessel. The proximal end 455 ofthe steering wire is coupled to the steering sleeve. In use, duringoccluder expansion, the steering sleeve is manipulated to move thedistal end of the cannula. The steering sleeve can be moved along thecannula to elevate the distal end 450 as depicted in FIG. 46A and 46B.Steerable occluder aligners can be designed so that the distal end ofthe cannula is positioned at the center point of the largest vessel inwhich the cardioplegia occluder is to be used. When used in smallervessels, the tip will lie below the centerline and can be rotated up bypulling the steering sleeve distally.

As described previously, the cardioplegia occluder can be used inconjunction with other cardiopulmonary bypass equipment or other cardiacsurgical equipment including blood cannulas, filter cannulas anddiverters in various combinations as integrated systems or as separatelyinsertable devices. In certain embodiments, a “one-stick” method isused, meaning that one incision is made into the aorta to insert thevarious pieces of equipment in either their integrated or separatelyinsertable configurations. In other embodiments, “two-stick” or“three-stick” (two or three aortic incision) methods are used. In someembodiments, the occluder is mounted on the blood cannula instead of thecardioplegia cannula. TABLE 1, located at the end of the DetailedDescription section, is provided to assist in describing the variouscombinations.

FIG. 47 shows a two-stick embodiment with a blood cannula 600 (adaptedto receive separately insertable filter 500 through a channel thereof)inserted through one incision and a separate cardioplegia occluder 1inserted through a second incision. The filter is carried through sidechannel 601 of the blood cannula. Either a modular filter cannula asshown (see Tsugita, U.S. Pat. No. 5,846,260, incorporated herein byreference, for more details) or an integral filter cannula (see Ser.Nos. 08/553,137, filed Nov. 7, 1995, 08/580,223, filed Dec. 28, 1995,08/584,759, filed Jan. 11, 1996, 08/852,727, filed Apr. 16, 1997, andU.S. Pat. No. 5,769,816, all incorporated herein by reference, for moredetails) can be used. In this embodiment, a diverter 700 has beeninserted in the region of the aorta 41 where the aorta intersects thebrachiocephalic artery 43, the left subclavian artery and the leftcommon carotid artery. In all cases described herein, whether one-, two-or three-stick and whether the various cannulas are integrated,separately insertable or certain cannulas are absent, the diverter maybe (i) absent, (ii) inserted only for the purpose of conducting thecardiac surgery, then removed at the completion of the surgery, or (iii)permanently installed in the aorta. The embodiment of FIG. 47 allows thecardioplegia occluder 1 to occlude the aorta distal to the infusionports 5 where cardioplegia solution is introduced to stop the heart.Downstream from the occluder 20, the filter 500 traps embolic debris andother unwanted material that is a byproduct of the surgical activity.Downstream from the filter, the blood cannula supplies blood from aheart lung machine to the aorta for circulation through the peripheralvasculature. The diverter 700, which is permeable to blood, furtherinhibits embolic material and other unwanted debris 800 from enteringthe cerebral vasculature by diverting it past the left common carotidartery and the brachiocephalic artery, which communicates with the rightcommon carotid artery.

FIG. 47A shows an embodiment of a two-stick model where the cardioplegiaoccluder 1 is adapted to receive the filter 500 through a channelthereof, and the blood cannula 600 is inserted through a separateincision. A diverter is present, but as previously described, thediverter may be installed permanently, inserted only for the purpose ofsurgery or absent altogether in all one-stick, two-stick or three-stickmethods. Other embodiments of the two-stick method include (i) anintegrated cardioplegia occluder and blood cannula with a separatefilter, either inserted through a filter cannula or separately inserted,(ii) a separately inserted cardioplegia occluder, a separately insertedblood cannula and no filter cannula, (iii) a blood cannula occluder witha filter inserted through a channel in the cannula as shown in FIG. 49,or mounted on the cannula and a cardioplegia cannula inserted through aseparate incision, and (iv) a blood cannula occluder and a cardioplegiaoccluder inserted through a separate incision and no filter.

FIG. 48 depicts a three-stick method with a separately insertedcardioplegia occluder 1, a separately inserted filter cannula 501 and aseparately inserted blood cannula 600. In this embodiment, the diverter702 is present, but any of the three diverter configurations could beutilized. In another embodiment, the filter is separately insertedwithout the use of a filter cannula, as shown in FIG. 50.

In other embodiments, a one-stick method is used. In one embodiment,depicted in FIG. 51, the cardioplegia occluder and blood cannula areintegrated 900, and the filter separately inserted through a channel inthe cannula In other embodiments, the filter may be mounted on thecannula or absent. Again, each combination has three possible diverterconfigurations.

In certain embodiments of the one-, two- and three-stick methodsdescribed above, the cardioplegia occluder may be replaced by a separateballoon cannula and a cardioplegia cannula. In such cases, the ballooncannula and the cardioplegia cannula can be separately inserted or canbe integrated with one another or each integrated with the filtercannula or the blood cannula.

Cardio- plegia Blood occluder Filter Cannula (CPO) (F) (BC) DescriptionONE-STICK* (1a) + + + Integrated CPO/BC; filter separately insertedthrough cannula (Fig. 51) or mounted on cannula (1b) + − + IntegratedCPO/BC TWO-STICK* (2a) + + + Filter inserted through CPO (Fig. 47A) ormounted on CPO 2b + + + Filter inserted through BC channel (Fig. 47) ormounted on BC 2c + + + Integrated CPO/BC; filter through filter cannulaor separately inserted 2d + − + Separately inserted CPO and BC 2e CP +BCO Occluder on BC; filter inserted through blood cannula occluder (BCO)(Fig. 49) or mounted on BCO, cardioplegia (CP) cannula separatelyinserted 2f CP − BCO Occluder on BC, CP cannula separately insertedTHREE-STICK* (3a) + + + Filter separately inserted through filtercannula or without cannula *It is to be noted that each combinationlisted has three possible variants as to a diverter. The diverter may be(i) absent, (ii) inserted only for the purpose of conducting the cardiacsurgery, then removed at the completion of the surgery, or (iii)permanently installed in the aorta.

While particular devices and methods have been described for using thecardioplegia occluder, once this description is known, it will beapparent to those of ordinary skill in the art that other embodimentsand alternative steps are also possible without departing from thespirit and scope of the invention. Moreover, it will be apparent thatcertain features of each embodiment as well as features disclosed ineach reference incorporated herein, can be used in combination withdevices illustrated in other embodiments. Accordingly, the abovedescription should be construed as illustrative, and not in a limitingsense, the scope of the invention being defined by the following claims.

We claim:
 1. A cardioplegia occluder for delivering cardioplegia to theaorta during cardiopulmonary bypass, comprising: a substantially rigidcannula having a distal region comprised of a material of at least 90Shore A with an outer surface, a distal end adapted to enter the aorta,a proximal end adapted to receive cardioplegia solution, a longitudinalcenter axis, a cardioplegia lumen which extends distally from saidproximal end and terminates and communicates with an infusion port insaid distal region for delivery of cardioplegia solution to the aorta;and an occluder mounted on the distal region of the cannula, saidoccluder expandable between a contracted condition and an expandedcondition, having a longitudinal center axis, wherein the occluder, whencontracted, is closely associated with the outer surface of the cannula,while the occluder expands upon activation to substantially occlude theaorta downstream of the infusion port, wherein, during use, saidoccluder isolates the ascending aorta from the peripheral vasculaturewithout substantial migration of the occluder within the ascendingaorta.
 2. The cardioplegia occluder of claim 1, wherein said distalregion of said substantially rigid cannula assumes a curved shape toallow self-centering.
 3. The cardioplegia occluder of claim 1, whereinsaid occluder is an inflatable balloon having an outer surfacesurrounding a chamber.
 4. The cardioplegia occluder of claim 2, whereinsaid occluder is an inflatable balloon having an outer surfacesurrounding a chamber.
 5. The cardioplegia occluder of claim 4, whereinsaid balloon covers a portion of said curved distal region of thecannula.
 6. The cardioplegia occluder of claim 1, wherein said occluderis mounted distal to the infusion port.
 7. The cardioplegia occluder ofclaim 3, wherein said cannula further comprises a lumen which extendsdistally from said proximal end of the cannula and terminates andcommunicates with an inflation port inside the chamber of said balloon.8. The cardioplegia occluder of claim 1, wherein said distal region ofsaid cannula is tapered.
 9. The cardioplegia occluder of claim 1,wherein said occluder after expansion assumes a generally sphericalshape.
 10. The cardioplegia occluder of claim 1, wherein said occluderafter expansion assumes a generally conical shape.
 11. The cardioplegiaoccluder of claim 1, wherein said occluder after expansion assumes agenerally elliptical shape.
 12. The cardioplegia occluder of claim 1,wherein said occluder is circumferentially disposed about the distalregion of the cannula so that the cannula runs approximately throughsaid longitudinal center axis of the occluder.
 13. The cardioplegiaoccluder of claim 1, wherein said occluder is circumferentially disposedabout the distal region of the cannula so that the cannula runs througha region displaced laterally from said longitudinal center axis of theoccluder.
 14. The cardioplegia occluder of claim 1, further comprising acannula open at said distal end, said distal end having a lumen, andsaid occluder, when contracted, is located inside the lumen in thedistal end of the cannula, and wherein, during use, said occluderexpands out the distal end of the cannula to substantially occlude theaorta downstream of the infusion port.
 15. The cardioplegia occluder ofclaim 3, wherein said balloon occluder has a first region of firstexpansion capacity and a second region of second expansion capacity, thefirst expansion capacity being less than the second expansion capacity,and wherein, during use, said second region expands preferentially andto a greater extent than said first region.
 16. The cardioplegiaoccluder of claim 15, wherein said first region of said balloon occluderis made of a flexible material of first thickness and said second regionis made of said flexible material of second thickness, the firstthickness being greater than the second thickness.
 17. The cardioplegiaoccluder of claim 15, wherein said first region of said balloon occluderis made of a material of first elastic modulus and said second region ismade of a material of second elastic modulus, the first elastic modulusbeing greater than the second elastic modulus.
 18. The cardioplegiaoccluder of claim 7, wherein said occluder is a foam-filled,self-expanding balloon.
 19. The cardioplegia occluder of claim 1,further comprising a flange associated with the cannula.
 20. Thecardioplegia occluder of claim 19, wherein said flange is mounted on thecannula, and wherein, during use, as the distal end of the cannula isinserted into the aorta, the flange contacts the surface of the aortaand prevents insertion of the cannula beyond a predetermined depth. 21.The cardioplegia occluder of claim 19, wherein said flange slidablyreceives the cannula.
 22. The cardioplegia occluder of claim 1, whereinsaid cannula further comprises a radiopaque marker band.
 23. Thecardioplegia occluder of claim 1, wherein said cannula further comprisesan aspiration lumen, which extends distally from the proximal end andterminates and communicates with said infusion port, and wherein, duringuse, said infusion port can alternately deliver cardioplegia solution oraspirate embolic debris and other unwanted material from the aorta. 24.The cardioplegia occluder of claim 1, wherein the distal region iscomprised of a material of at least 92 Shore A.
 25. The cardioplegiaoccluder of claim 1, wherein the distal region is comprised of amaterial of at least 95 Shore A.
 26. The cardioplegia occluder of claim1, wherein the material of the distal region is selected from the groupconsisting of PEBAX nylon, composite plastic with fibers, polyethylenereinforced with nitinol braid, stainless steel and nitinol.
 27. Thecardioplegia occluder of claim 1, wherein the entire cannula is rigid.28. The cardioplegia occluder of claim 1, further comprising a cuttingblade.
 29. A method for administering cardioplegia, comprising the stepsof: providing a substantially rigid cannula having proximal and distalends, and a proximal and a distal region, a balloon occluder mounted onthe distal region and communicating with an inflation lumen extendingproximal from the occluder, a port on the cannula proximal the balloon,the port communicating with a first lumen which extends proximally fromthe port, wherein the distal region is comprised of a material of atleast 90 Shore A; making an incision in the aorta; inserting the distalend of the cannula and the occluder through the incision in the aorta;expanding the occluder to occlude the aorta downstream of the infusionport; and infusing cardioplegia solution through the port, wherein theoccluder isolates the ascending aorta from peripheral circulationwithout substantial migration within the ascending aorta.
 30. The methodof claim 29, further comprising a second lumen which merges andcommunicates with the first lumen proximal the port.
 31. The method ofclaim 29, wherein said cannula carries a cutting blade, and wherein thestep of making an incision in the aorta is performed by the cuttingblade.
 32. The method of claim 29, wherein the occluder, whencontracted, is adapted to conform to the outer surface of the cannula.33. The method of claim 29, wherein the infusion port is proximal theoccluder.
 34. The method of claim 29, wherein the cannula furthercomprises an arterial return lumen which extends distally from theproximal end of the cannula and terminates and communicates with asecond port.
 35. The method of claim 34, wherein the second port isdistal the occluder.
 36. The method of claim 29, further comprising thestep of placing the patient on cardiopulmonary bypass.
 37. The method ofclaim 29, further comprising the steps of contracting the occluder andremoving the cannula and the occluder from the aorta.
 38. The method ofclaim 30, further comprising the step of aspirating fluid from the aortaby applying negative pressure to the second lumen.
 39. The method ofclaim 29, further comprising the steps of performing a coronary arterybypass graft procedure.
 40. The method of claim 29, wherein the distalregion of the cannula is bent at an angle of approximately 90 degrees.41. The method of claim 29, wherein the distal region of the cannulaincludes a curved region.
 42. The method of claim 29, wherein theballoon covers a portion of the curved region.
 43. The method of claim29, wherein the cannula further comprises an inflation lumen whichextends distally from the proximal end of the cannula and terminates andcommunicates with an interior of the balloon.
 44. The method of claim29, wherein the distal region of the cannula is tapered.
 45. The methodof claim 29, wherein the occluder expands to assume a generallyspherical shape.
 46. The method of claim 29, wherein said balloonoccluder is made of an elastic material.
 47. The method of claim 29,wherein the cannula further comprises a suture flange.
 48. The method ofclaim 29, wherein the entire cannula is substantially rigid.